Could you explain how to set up the equation and how to approach how to answer this question. it's already been answered just explain how to approach it

11 An airplane flies horizontally at an altitude of fakean and pastry directly over a tracking telescope on the ground. When the angle of elevation Ci e. the angle at the telescope measured upwards from the horizontal to the airplane ) is L , this angle is decreasing at a rate of 40'rad / hip . How fast is the airplane travelling at that time ? 101 X - 7. adjacent X 6 tanG opposite 6 6 * = 6 coto X -7 d at ( x ) = d dx 6 (sc2 A do d+ Sin 2 0 - 6 ( - 40 ) Sin ? / JZ EX ( - 40 ) 0 .5 2 Slow 10 Karate el- 6 (2)2 ( = 40 )x 79 of longs off 19 fortuneb ban jamin = =6(4) (=40) (-24) (-40 ) 960 rad / hr